steinhart.bas

Coding and general discussion relating to user created compiler modules

Moderators: David Barker, Jerry Messina

Post Reply
geekything
Posts: 16
Joined: Mon Feb 11, 2008 10:06 pm

steinhart.bas

Post by geekything » Wed Jun 18, 2008 10:50 am

Hi there,

Did anyone ever try to get this working?

I've assembled a breadboard 18F4550 circuit that matches the schematic and am using AN0 for the thermistor. The display is on Port D/E and works perfectly. Oh, and I picked up a 1% 10K resistor as per the recommendation.

However, I get seemingly random numbers on the display.

One thing I'm a little unclear about...I know the T25 value for my thermistor (it's 10K) and I know the Beta (it's 3892). The constants in the listing don't seem to bear much resemblance to any real-world T25 or Beta, unless I'm missing something:

Code: Select all

 Const T25Val = 0.0033540                    // Thermistor's t25 value
 Const ThermistorBVal = 1.0 / 3489.0         // Thermistor's B value
Is the above saying the Beta is 3489? What the heck about the T25 value?!

Any help with this or Thermistors in SF would be greatly appreciated :)

TIA,

-marc

geekything
Posts: 16
Joined: Mon Feb 11, 2008 10:06 pm

Post by geekything » Fri Jun 20, 2008 4:14 pm

I got everything working now. I'm still not sure about the T25 constant, but my setup seems to be within 0.1c of the readings on my commercial infrared thermometer so I'm happy :)

-marc

Post Reply